Refining of oils



Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE Socony-Vacuum Oil Company, Incorporated, New York, N. Y, a corporation of New York No Drawing. Original application June 27, 1936, Serial No. 87,764. Divided and this application September 8, 1938, Serial No. 228,919

2 Claims. (Cl. 196-13) This invention relates to the refining of peable for controlling the effectiveness and selectivtroleum, and has to do particularly with the reity of said selective solvent agents, wherein the fining of petroleum fractions by processes of secontrol is effected by modification of the selective solvent extraction. lective solvent power of said liquid solvents by This application is a division of my prior apdissolving therein diiie'rent or varying amounts 5 plication, S. N. 87,764, filed June 27, 1936, and of appropriate inorganic compounds. which has now matured into Patent No. 2,133,691. The most important advantage of such a proc- An example of the type of process with which ess probably consists in the discovery that the sethis invention is concerned is that of fractionalectivity of certain normally poor solvents not tion as between parafiinic and naphthenic only may be increased to'a very desirable degree, 10

compounds of like boiling range, but of diiierent but that a great flexibility of processing is therechemical and physical characteristics, to efiect a by provided, since concentrations of the inorganic separation of the compounds of a parafiinic compound in the solvent may be varied to suit nature from the compounds of a non-paraffinic any desired extraction temperature.

or naphthenic nature by means of a selective Examples of the modified solvent reagents or 15 solvent showing diiierent solvent powers for the solutions which may be thus used, are solutions two classes of hydrocarbons. of lithium halides in pyridine, solution of cal- The effectiveness of such a fractionation or cium nitrate in pyridine, and solution of lithium separation operation as that above described, may chloride, calcium nitrate, lithium bromide, lithbe measured, and is measured herein, by the visium iodide, or lithium acetate in picoline. 2o

cos tyyso-caiied This In general any combination of a selective solv sc s yv y- Proposed by Hill and vent and salt is effective in which the salt dis- Coates, Ind. & Eng. Chom- 1928, p 641, iS solves in the solvent to a sufiicient extent to afiect valuable indication of the P -i of the selectivity of the solvent, provided the salt an o l fraction, SinCe Said Yalue mdlcates is substantially non-reactive to oil and solvent 25 increasing freedom from Constituents highly and remains in solution in substantial amounts naphthenic with decrease in numerical value in the presence of 1 Specific examples of Suit of the co st t The for present-day lubri' able salt-solvent combinations which I have oant of Pennsylvania Origin, (I10t $0 1Vent found, up to the present, to be useful for this purfined) is around- 0-800 to Wlth slmliar lubn pose, are the solutions of lithium chloride, bro- 30 cant fractio s from other Sources rangmg up to mide, or iodide, or of calcium nitrate in pyridine 0.900. or picoline and combinations thereof, provided An important ob ect of this invention is a novel they are mutually inert-h method for the separation of petroleum fractions To Show the ffe tivene of these salt solvent of Similar boiling points etc-i but of differing or modified solvent reagents for the purposes in- 35 chemical i i tm P t i advantage 9 dicated, an example is here noted wherein an oil g g g isgi g fi fgggggg g fi was extracted with four times its volume of a 5% a i object of this invent-ion to solution (about /5 saturated) of lithium chloride vide novel refining agents for the above purposes, m pyndme at 100 The resuitmg two layers and to improve known liquid Selective Solvent were separated. The upper or oil layer was then agents for this purpose, and to provide a process cooled to about 25 C.,result1ng 1n the separation for using these novel and improved selective of an additional extract layer which was added to the original solvent layer. The oil layer consolvent agents.

one object of this invention is to provide a tamed some pyr1d1ne,wh1ch was removed by disprocess of refining petroleum lubricant stocks iillation, (leaving y a trace of lithium chlowhich is applicable generally to any pet ride), leaving a rafiinate of increased value, as lubricant oil stock which contains fractions of shown in the tabular data s ted below. The good lubricating value, t also contains extract layer was distilled to separate the pyridine phaltic and/or naphthenic matter to produ therefrom and the 011 removed from the residua 50 therefrom a refined lubricating oil of high quality Salt by decantatlon.

having a good viscositwgravitywonstam, and In a second example, another portion of the other desirable qualities. same oil stock was treated twice successively with A most important object of this invention is to two Volumes each of a 4% (about half saturated), provide a process of this nature which is adaptsolution of calcium nitrate in pyridine at 50 C. 55

The lower layer was withdrawn, distilled, and decanted as above to recover the pyridine and salt. The upper layer, or rafiinate, was heated to remove pyridine by distillation.

The properties of the original oil and of the two rafiinates are shown in the following table:

It will be noted that the treatment resulted in a greatly improved rafilnate. The two extractions are about equally efiicient, but it should be observed that the calcium nitrate-solvent procedure involved a double extraction and that the lithium chloride-solvent procedure involved a higher temperature, which permitted a higher molar concentration of the salt. It should be noted also that if pyridine alone is used as the selective solvent, a temperature of below C. is ordinarily necessary to cause separation into two layers, and the improvement of the raffinate under these conditions is very much less.

Calcium nitrate in pyridine cannot be used at much higher concentration or temperature than shown above without precipitation of the salt, resulting in the mixing of the two layers. Lithium chloride in pyridine can be used up to about 120 C. and 7% concentration, with some increase in selectivity of the selective solvent.

The salt, solvent, concentration and temperature chosen should be such that the salt remains in solution in the solvent under conditions of treatment, as pointed out hereinbefore.

In the following claims, the term solvent refining is used to designate the fractionation of petroleum fractions to separate constituents of varying chemical properties by means of a solvent having selective solvent power for one of the classes of constituents.

I claim:

1. In the method of solvent refining lubricant oil by means of a selective solvent comprising pyridine, the steps which comprise dissolving calcium nitrate in said pyridine, mixing the pyridine solution of calcium nitrate with oil to be refined, effecting the formation of a rafiinate and an extract phase within the mixture thus obtained, separating the said phases, and freeing the raifinate phase of solvent and salt to form a defined oil of greater parafllnicity.

2. In the method of solvent refining lubricant oil by means of a selective solvent comprising pyridine, the steps which comprise dissolving in the pyridine about 4% of calcium nitrate, mixing the pyridine solution of calcium nitrate with oil to be refined at a temperature of about 50 C. effecting formation of rafiinate and extract phases from the mixture thus obtained, separating the phases, and freeing the raflinate phase of solvent and salt to form a refined oil of lower viscositygravity-constant.

ALFRED W. FRANCIS.

CERTIFICATE OF CORRECTION.

Patent No. 2,l} .2,959 January 5, 1959..

ALFRED w. FRANCIS It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 25, claiml, for the word "defined" read refined; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of March, A. D. 1959., v

Henry Van Arsdale.

(Seal) Acting Commissioner of Patents. 

